Portable power supply system for an electrically driven work machine and a work machine equipped with such a power supply system

Abstract

A portable power supply system supplies a remotely controlled, electrically driven work machine with electrical power. The work machine includes continuous tracks and is equipped with a maneuverable arm that carries a tool at its free end. An electric motor is connected to a hydraulic pump and supplies the machine with a hydraulic medium. The work machine is connected under normal operation to a primary source of power via an electrical cable. The primary source of power includes a fixed alternating current electricity distribution grid at the location. In order to be able to supply the current that is required it includes a DC energy-storage arrangement that, including a secondary source of power, can store energy and, when necessary, supply energy in electrical form. A coupling arrangement makes it possible to choose between connecting the motor to the primary or the secondary source of power.

What is claimed is: 
     
       1. A portable power supply system for an electrically driven demolition robot, the electrically driven demolition robot comprising a propulsion means with continuous tracks with which the demolition robot can be driven, a maneuverable arm and a coupling tool at a free end of said maneuverable arm, wherein the electrically driven demolition robot is connected to a primary source of power during normal operation via an electrical cable and said primary source of power including a fixed alternating current (AC) electricity distribution grid at a job site, the portable power supply system comprising:
 an electric motor connected to a hydraulic pump to supply the operating means of the demolition robot with a hydraulic medium, 
 a secondary source of power comprising a direct current (DC) energy-storage arrangement with the ability to store and to supply electrical energy, 
 a rectifier for the conversion of AC from the fixed electricity distribution grid at the job site to DC for the energy-storage arrangement, and 
 a coupling arrangement arranged between the primary source of power, the secondary source of power and the electric motor such that said coupling arrangement allows the secondary source of power to be connected to the electric motor in order to drive the electrically driven demolition robot, as needed, 
 wherein the coupling arrangement comprises a DC bus to which the rectifier is connected in order to supply DC from the primary source of power to the DC bus, a control circuit which is connected to the DC bus and controls and monitors the levels of voltage that are supplied from the DC bus to the electric motor through continuously sending and receiving signals from the rectifier, an inverted rectifier, and the secondary source of power that are connected to the DC bus, and further measures the instantaneous state of the DC bus, 
 wherein the secondary source of power can solely supply the electrical power that is required to the demolition robot in the absence of power from the primary source of power, and can also serve as a supplemental source of power to the primary source of power to operate the demolition robot as needed. 
 
     
     
       2. The portable power supply system according to  claim 1 , wherein the electric motor is of three-phase alternating current type and the coupling arrangement comprises the inverted rectifier in order to reform the DC that is supplied via the control circuit from the DC bus to AC for said three-phase alternating current motor. 
     
     
       3. The portable power supply system according to  claim 1 , wherein the DC energy-storage arrangement is designed as an integral part of the demolition robot. 
     
     
       4. The portable power supply system according to  claim 1 , wherein setting of the electrically driven demolition robot for operation by means of the secondary source of power can be carried out manually by an operator through the setting of a switch or button or automatically through the measurement and recording, by means of the control circuit, of the power surplus or power deficit that arises in the DC bus of the coupling arrangement. 
     
     
       5. The portable power supply system according to  claim 2 , wherein, when set into the operating condition in which reserve power is used that includes electrical energy from the secondary source of power, the system is arranged to supply a three-phase rated voltage at 400 V and a frequency of 50 Hz AC to the electric motor of the electrically driven demolition robot with the nominal power that is required to drive the electrically driven demolition robot according to the specified rating. 
     
     
       6. The portable power supply system according to  claim 1 , wherein the DC energy-storage arrangement with the integral secondary source of power comprises at least one of a battery or an electrical accumulator. 
     
     
       7. The portable power supply system according to  claim 1 , further comprising a control unit to be carried by an operator who walks beside the electrically driven demolition robot and controls various motions of said electrically driven demolition robot in a wireless manner through radio control or through a cable,
 wherein the control unit can be switched between an operating condition for an addition of back-up power which is the secondary source of power, in which the operating condition is in an active condition that is indicated to the operator with the aid of a symbol labeled “On” which is illuminated on a display on the control unit, and an operating condition in which the power supply system is arranged to supply a rated voltage to the electric motor of the demolition robot with the nominal power that is required in order to drive the motor of the demolition robot according to the specified rating. 
 
     
     
       8. An electrically driven demolition robot comprising:
 a chassis with a propulsion means including continuous tracks, 
 a control unit to be carried by an operator who walks beside the electrically driven demolition robot and controls various motions of said electrically driven demolition robot in a wireless manner by radio control or through a cable, 
 a maneuverable arm coupling a tool at a free end of said maneuverable arm, 
 a power supply system supported by the chassis comprising an electric motor connected to a hydraulic pump to supply the operating means of the demolition robot with a hydraulic medium, 
 a primary source of power to which the demolition robot is connected during normal operation via an electrical cable and said primary source of power including a fixed alternating current (AC) electricity distribution grid at a job site, 
 a secondary source of power comprising a direct current (DC) energy-storage arrangement with the ability to store and to supply electrical energy, 
 a rectifier for the conversion of AC from the fixed electricity distribution grid at the job site to DC for the energy-storage arrangement, 
 a coupling arrangement arranged between the primary source of power, the secondary source of power and the electric motor such that the coupling arrangement allows the secondary source of power to be connected to the electric motor in order to drive the electrically driven demolition robot, as needed, 
 wherein the coupling arrangement comprises a DC bus to which the rectifier is connected in order to supply DC from the primary source of power to the DC bus, a control circuit which is connected to the DC bus and controls and monitors the levels of voltage that are supplied from the DC bus to the electric motor through continuously sending and receiving signals from the rectifier, an inverted rectifier, and the secondary source of power that are connected to the DC bus, and further measures the instantaneous state of the DC bus, 
 the control unit can be switched between an operating condition for an addition of back-up power which is the secondary source of power, in which the operating condition is in an active condition that is indicated to the operator with the aid of a symbol labeled “On” which is illuminated on a display on the control unit, and an operating condition in which the power supply system is arranged to supply a rated voltage to the electric motor of the demolition robot with the nominal power that is required in order to drive the motor of the demolition robot according to the specified rating, and 
 the secondary source of power can solely supply the electrical power that is required to the demolition robot in the absence of power from the primary source of power, and can also serve as a supplemental source of power to the primary source of power to operate the demolition robot as needed. 
 
     
     
       9. The electrically driven demolition robot according to  claim 8 , wherein the electric motor is of three-phase alternating current type and the coupling arrangement comprises the inverted rectifier in order to reform the DC that is supplied via the control circuit from the DC bus to AC for the three-phase alternating current motor. 
     
     
       10. The portable power supply system according to  claim 1 , wherein the fixed alternating current electricity distribution grid is rated a voltage of 400V and a frequency of 50 Hz. 
     
     
       11. The electrically driven demolition robot according to  claim 8 , wherein the fixed alternating current electricity distribution grid is rated a voltage of 400V and a frequency of 50 Hz. 
     
     
       12. The portable power supply system according to  claim 1 , wherein the control circuit is configured to store power in the secondary source of power when the voltage exceeds an amount of power required to operate the demolition robot and draws power from the secondary source of power when the voltage is below said amount of power. 
     
     
       13. The electrically driven demolition robot according to  claim 8 , wherein the control circuit is configured to store power in the secondary source of power when the voltage exceeds an amount of power required to operate the demolition robot and draws power from the secondary source of power when the voltage is below said amount of power.